The invention relates to an electron source comprising a substrate with a heating element arranged at least at the location of an electron-emissive part of the electron source.
The invention also relates to a method of manufacturing such an electron source and to a cathode ray tube provided with such an electron source.
Electron sources of the type mentioned above are used in cathode ray tubes, particularly in flat display devices in which one electron source is often used for each column of pixels.
An electron source of the type mentioned in the opening paragraph is described in U.S. Pat. No. 4,069,436. The electron source described in this Patent has an electron-emissive layer which is separated from an underlying heating element by an insulating layer, which heating element is in its turn separated from the substrate by an insulating layer. Although this substrate is preferably chosen to be as thin as possible so as to reduce the overall dissipation, this causes problems because mechanical causes or thermal tensions may lead to breakage when using a small thickness. As the substrate should therefore have a minimum thickness, it retains a large thermal capacity. Consequently, a large part of the supplied energy is lost when (parts of) the substrate are heated so that the actual emissive material is not heated optimally, which is at the expense of the electron emission. Said large thermal capacity also causes a long reaction time of the cathode.